Dear Rimantas
 
in our beekeeping magazines there has been a discussion about the use of
oxalic acid for a long time.
 
Do my opinion it is rather dangerous to use this acid and it is far more
dangerous than formic acid. Steer clear of it.
 
The reasons are
 
- oxalic acid is a poison (MAK-values in USA 1 mg/m3 to my opinion)
especially when   you spray it one should use gloves, protecting glasses
or even a gas mask.   Incorporation of oxalic acid may cause damage of
human heart and kidneys.
- oxalic acid is easy to solv in water and so in honey too. If you use
it in the   wrong season you can contaminate your honey.
- the success of treatment isn't better than with other substances.
- it is a lot of work to take out one comb after the other and spray the
substance on   them.
 
If you want to spray an acid onto the bees you better should use lactic
acid. It works rather good and is also used in foods.
 
> Some beekeepers like formic acid. But sometimes bees are killed. The reason is supposed to be very great amount of Varroa mites in a colony. It means too much holes in a body of everyone bee.
 
This is also a very adequate mean for fighting varroa mites. Perhaps the
best way to use by a long time evaporating system. Formic acid also
kills mites within capped cells.
 
> Some use a net on a hive bottom and an exciting means, for eg : garlic, horse-radish, juniper, hop, etc.
 
I've never heard of that. Does it work? I would be afraid that honey
absorbs the smell of these substances.
 
Dr. Reimund Schuberth
beekeeper in Germany (Bavaria)
insemination station
queen breeding of Carniolan queens